<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var height = parseFloat(prompt("请输入高度"));
        var r = parseFloat(prompt("请输入半径"));
        var result = 1/3 * Math.PI * Math.pow(r,2) * height;
        alert("结果是:"+result);//250000 
    </script>
</body>
</html>